1. Field
The present disclosure relates to a display device and a method for controlling the same.
2. Description of the Related Art
The human eye has a feature that it is more sensitive to a luminance difference in a dark region than that in a bright region. Such a feature is well known even as Weber's law. Further, such a feature is well revealed even in the luminance characteristic of an image that is displayed on a display device.
In particular, the non-linear luminance characteristic due to a digital input of a display device causes a problem in that the number of grayscale or grayscale values being expressed in a dark region of an image becomes insufficient and thus grayscales are not smoothly represented. Reduction of the number of grayscales in such a low-grayscale region causes minuteness of a dark image not to be expressed and causes false contours to occur.
An existing representative method for increasing the number of grayscales being expressed may be a dithering method. The dithering is a technology to express insufficient color information as a density combination of similar colors in the case where an image that is composed of upper bits is output through a device that supports lower bits in addition to the upper bits.
In particular, since the display device uses an LED module that is a self-luminous element, the luminance is high, and a refresh rate is also relatively high. However, the refresh rate differs depending on the grayscales, and in low grayscales, the refresh rate becomes relatively lower due to the structure of the display device. Accordingly, in the case of a high-luminance and high scan rate display device, the luminance difference between respective levels of the low grayscale value becomes larger, and in the case of performing dithering, the luminance difference between surrounding pixels becomes greater in the low-grayscale image to cause noise to occur. A viewer may feel such noise is greater in a dark place than in a bright place.
Accordingly, there has been a need for techniques to solve the problem of image quality deterioration that a viewer feels or sees from a low-grayscale image on a display device.